Method for operating a water-conducting domestic appliance

ABSTRACT

A method for operating a dishwasher is provided. The method includes heating a first amount of liquid in a first partial program step; at least partially storing the heated first amount of liquid in the interior of a liquid reservoir, wherein the heated first amount of liquid is in heat-conducting contact with the interior of a tub; circulating a second amount of liquid in a second partial program step; and emptying the liquid reservoir when the second partial program step has been completed.

The invention relates to a method for operating a water-conducting domestic appliance.

From DE 27 30 489 a household dishwasher is known, in which for the cleaning of items to be washed a washing program having a multiplicity of program steps is performed, which has at least two partial program steps, during which washing liquor, for example water mixed with detergent or rinse aid, is heated, where the dishwasher has at least one tub for accommodating items to be washed and a liquid reservoir in heat-conducting contact with the tub. It here permits the liquid reservoir in thermal contact with the tub to heat water, for example prior to its use in a washing step. This can take place by means of a temperature difference relative to the environment of the dishwasher and/or through the waste heat of the washing liquor circulated in the treatment compartment. An energy saving can thereby be achieved.

The object of the invention is to specify a method with which the energy consumption can be further reduced.

The inventive method for operation of a dishwasher, in particular a household dishwasher, has at least the following steps:

-   -   a first amount of liquid is heated in a partial program step,     -   the heated first amount of liquid is stored, at least partially         in heat-conducting contact with the interior of a tub, in the         interior of a liquid reservoir,     -   in a further partial program step a second amount of liquid is         heated, and     -   emptying of the liquid reservoir, when the further partial         program step has been completed.

The inventive method thus allows regaining of the use of heat energy of liquids, in particular of heated liquids, which is otherwise lost upon being pumped out into a domestic wastewater disposal system.

In a preferred embodiment it is provided for the circulated amount of liquid to be heated at least for a time in the further partial program step, so that temperatures can also be achieved which could not be attained only through the use of recovered heat energy. It can however also be provided for heating to be dispensed with in the further partial program step, and instead to use recovered heat energy to heat liquid.

It is here preferably provided for the circulated amount of liquid only to be heated to a temperature equal to or below the temperature of the liquid stored in the liquid reservoir, so that no unnecessary energy need be applied to heat the liquid stored in the liquid reservoir.

In a first, preferred embodiment, it is provided for the liquid reservoir and the tub to be emptied simultaneously, while in a second, alternative embodiment, it is provided for the tub to be emptied first, followed then by the liquid reservoir.

The partial program steps preferably comprise at least one cleaning step and one rinsing step, where during both partial program steps liquids are heated in each case. During the cleaning step, detergent is here added and the circulated liquid or washing liquor heated to, for example, up to 65° C. In the rinsing step on the other hand, wetting agents are added, which are in particular intended to ensure a smear-free drying process for the items to be washed, where temperatures of for example 70° C. are reached in this step.

At least one third partial program step without the heating of liquid can further preferably be provided for between the two partial program steps. This can here preferably take the form of an intermediate rinse step, which serves to remove residues of liquid or washing liquor mixed with detergent remaining in the tub and the pump system of the dishwasher, in order to ensure that detergent residues and wetting agent added in the rinsing step do not have mutually negative effects.

Finally it can preferably be provided for, that prior to a partial program step, during which liquid is heated, one or more pre-rinse steps without heating of liquid are provided, in which liquid stored in the liquid reservoir is used. The pre-rinse serves to remove heavy soiling from items to be washed.

The invention further includes a dishwasher, which is embodied for execution of the inventive method.

The invention is explained below on the basis of a drawing.

Wherein:

FIG. 1 shows a schematic representation of a dishwasher for execution of the inventive method:

The dishwasher 2 has a tub 6 to accommodate items to be washed (not shown), which for example can be placed in extendably mounted crockery baskets (not shown). In order for the items to be washed to have liquid or washing liquor, that is water mixed with detergent or rinse aid, applied to them, a spray arm 8 is provided in the tub in the present exemplary embodiment. A multiplicity of spray arms can however be provided. A circulation pump 10 is provided to supply the spray arms 8 with washing liquor, which is connected in a liquid-conducting manner with a sump arranged in the base area of the tub 6, in which the washing liquor dripping off the items to be washed is collected. A motor 12 is provided to drive the circulation pump 10, which is connected to a control device 14 of the dishwasher 2. A heating element (not shown) can be provided to heat the circulated washing liquor.

A liquid reservoir 4 in heat-conducting contact with the tub 6 is provided, in which an amount of liquid can be temporarily stored. A drainage line 24 is provided in the tub 6 for emptying the liquid reservoir 4, which can be opened and closed by means of a drain valve 18, where the drain valve 18 is connected with the control device 14 via a control line 16.

Finally a return line 26 is provided, with which it is possible to convey washing liquor from the tub 6 back into the liquid reservoir 4. A return valve 20 is provided for the opening and closing of the return line 26, which is likewise connected to the control device 14 via a control line 18. Further valves can in addition be provided, to block an inlet line to the spray arm 8 in the tub 6, if washing liquor is to be conducted into the liquid reservoir 4 through the return line 26 by means of the circulation pump 10. A multi-way valve embodied as a water distributor can further be used instead of individual valves, which for example has a disk adjustable by means of a motor.

For the cleaning of items to be washed a washing program comprising a multiplicity of program steps is run, which can for example encompass the program steps pre-rinse, washing, intermediate rinse step and final rinsing, plus drying. The water or washing liquor, that is water mixed with detergent or rinse aid, is here heated during at least two of these program steps, for example during the washing and the rinsing step. A change of washing liquor involving the circulated washing liquor takes place between the partial program steps, that is after the conclusion of a partial program step the dishwasher is once more filled with liquid or water respectively.

A pre-rinse step can for example be performed, after an amount of liquid has flowed into the tub 6 via conduit means (not shown). The amount of liquid is circulated from the circulation pump 10 after corresponding actuation of the motor 12 by means of the control device 14, and fed to the spray arm 8.

After completion of the pre-rinse cycle, the amount of liquid is directed through the return line 26 into the liquid reservoir 4 after opening of the return valve 20, where a closed drain valve 18 prevents the tub 4 being emptied once again.

Finally, for the cleaning step the tub 6 is filled with an amount of liquid via conduit means (not shown), and the amount of liquid circulated by means of the circulation pump 10 and simultaneously heated.

After conclusion of the cleaning step the amount of liquid can be conveyed from the tub 6 into the liquid reservoir 4 through opening of return line 26 by means of actuation of the return valve 20.

In an intermediate rinse step the tub 6 is once more filled with an amount of liquid and the liquid then circulated with the circulation pump, without being heated. A heating takes place solely through the heat transition from the liquid reservoir 4 into the interior of the tub 6, as the liquid stored in the liquid reservoir 6 has a higher temperature than prevails in the interior of the tub 6. After completion of the intermediate rinse step, both the tub 6 and the liquid reservoir 4 are emptied. This can take place consecutively, starting with the tub 6, or simultaneously.

Subsequently in a last step the tub 6 is once more filled with an amount of liquid for execution of a rinsing step, and the liquid then circulated with the circulation pump, while being further heated.

After conclusion of the rinsing step, the tub 6 can be emptied by means of a conduit means, which is not shown, which allows liquid to be directed into a domestic wastewater disposal system.

Provision can also be made, while the amount of liquid present in the tub 6, that is water mixed with wetting agent or rinse aid, is then routed into the empty liquid reservoir 4 through the return line 26.

In the case of a renewed program start, the amount of liquid temporarily stored in the liquid reservoir 4 is directed into the tub 6 by opening of the drain valve, and used to perform a pre-rinse step.

Notwithstanding the described program sequence, an energy saving can also be achieved with the inventive method in the case of modifications to the program sequence, in which during the intermediate rinse and/or pre-rinse step a heating of the liquid or washing liquor is also provided for, or in which the intermediate rinse and or pre-rinse step are blanked out.

LIST OF REFERENCE CHARACTERS

-   2 Dishwasher -   4 Liquid reservoir -   6 Tub -   8 Spray arm -   10 Circulation pump -   12 Motor -   14 Control device -   16 Inlet valve -   18 Drain valve -   20 Return valve -   22 Inlet line -   24 Drainage line -   26 Return line 

1-11. (canceled)
 12. A method for operation of a dishwasher, the method comprising: heating a first amount of liquid in a first partial program step; at least partially storing the heated first amount of liquid in the interior of a liquid reservoir, wherein the heated first amount of liquid is in heat-conducting contact with the interior of a tub; circulating a second amount of liquid in a second partial program step; and emptying the liquid reservoir when the second partial program step has been completed.
 13. The method of claim 12, wherein the dishwasher is a household dishwasher.
 14. The method of claim 12, wherein the circulated second amount of liquid is heated at least at times in the second partial program step.
 15. The method of claim 12, wherein the circulated second amount of liquid is heated only to a temperature that is one of equal to and below a temperature of the first amount of liquid stored in the liquid reservoir.
 16. The method of claim 12, wherein the liquid reservoir and the tub are emptied simultaneously.
 17. The method of claim 12, wherein first the tub is emptied and then the liquid reservoir is emptied.
 18. The method of claim 12, wherein the first partial program step is a cleaning step and the second partial program step is a rinsing step.
 19. The method of claim 12, wherein a third partial program step is provided between the first and second partial program steps without heating at least one of the first and second amount of liquid.
 20. The method of claim 19, wherein the third partial program step is an intermediate rinse step.
 21. The method of claim 12, wherein the first amount of liquid stored in the liquid reservoir is used before at least one of the first and second partial program step.
 22. The method of claim 21, wherein the first partial program step is a pre-rinse step without heating the first amount of liquid.
 23. A dishwasher, comprising: a liquid reservoir; a tub; a heater to heat a first amount of liquid in a first partial program step; a storage to at least partially store the heated first amount of liquid in the interior of the liquid reservoir, wherein the heated first amount of liquid is in heat-conducting contact with the interior of the tub; a circulator to circulate a second amount of liquid in a second partial program step; and an emptying device to empty the liquid reservoir when the second partial program step has been completed. 